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Jan. 6, 1942. R. s. ELLIS 2,258,652

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' IQUxEL/ SCOTT'LU By' Lw-N R. s. `ELLIS 2,268,652

MEANS FOR SEPARATING PARTICLES OF SOLID MATERIAL BY FLOTATION Jan. 6, 1942.

Filed April 19, 1959 '7 Sheets-Sheetl 7 @NAN Patented Jan. 6, 1942 UNITED STATES PATENTA oEFlcE `MEANS FOR SEPARATIN G PARTCLES OFV" SOLID MATERIAL BY FLOTATION aussen' scott Ellis, Vineland, N. J. Application April 19, 1939, serial No. 268,667

9y Claims.

My present invention relates to methods and means of the same general character as disclosed in Letters Patent of the United States No. 2,104,537 granted to me January 4, 1938, andNo. 2,146,672 granted to me February "l, 1939, and is applicable to any material particlesA ofk different sizes or specific gravity, or both,for instance, natural sands, comminuted stone,coal, vegetable grains, or any other substances, bythe application thereto of water or other fluid or mixture of uids under pressure to effect flotation thereof, and consequent separation of such particles.

The apparatus disclosed in said patents includes a plurality of separator caslngs, utilized as distinct. receptacles for the material to be treated, disposed in a vertical series; and connected in series relation by conduits through which solid material which is not precipitated in the lowermost receptacle ls delivered into the next higher receptacle, and the material which is not precipitated in the second receptacle is delivered into a third receptacle, and so on, the materials precipitated in the several receptacles being discharged separately from the bottoms thereof, and the finest materials, liinallyy separated by otation, being discharged from the top receptacle.

In the form of my invention chosen for illustration herein, as in each of said patents, the separator casing has a conical portion with its apex extending vertically downward, and has an inlet conduit for the material to be separated extending tangentially into one side thereof below the top, and an outlet conduit extending tangentially from the upper part of the casing, whereby the material stream ows circumferentially and centrifugal separation is effected. An axial inlet conduit for the flotation fluid extends vertically through said casing in coaxial relation therewith. That conduit is connected with two distinct flotation fluid supply conduits, respectively' above and below said casing, through.

either or both of which flotation fluid may be delivered into the casing under pressure and including means for varying the effective area of the orice through which the dotation fluid is the flotation lluidin the apparatus; which tends to vary with momentary variations in the quantity of raw solid material supplied to the apparatusviscoslty of the fluid, power supply, etc. My` present invention provides improved means for controlling and regulating such back pressure and the centrifugal force/ available for separation, by varying the pressure under which the otation fluids are supplied to the apparatus.

Such control `is effective with respect to one or more columns of liuid, as to their relative pressures and rate of flow, and with reference to one or more adjustably variable outlets for fluid.

. Such control is applied to a pump motor, or mo tors, which maybe either electrically or mechanic'ally energized, to produce the initial pressure upon said fluids. .l f

My invention includes the various novel features of construction, arrangement, and vmethod of operation hereinafter more definitelyl specified.

In said drawings; Fig. I is a diagrammatic elevation, partly in section, of apparatus exemplifying my invention, particularly designed to em-A ploy water as a flotation and cleansing fluid. Fig. II is a diagrammatic elevation, partly in section, of the iiuid impelling means indicated in the lower portion of Fig. I, but on a larger scale. Fig. III is a diagrammatic elevation, partly in section, of a portion of the apparatus at the upper end of Fig. L'but on a larger scale. Fig. IV is a larger longitudinall sectional'view of one of the ball valve caslngs for controlling the flotation fluid, of which two are-shown at the right of Fig.` III. .'Fig.' V is a diagrammatic elevation, partly in section, similar to Fig. III, but showing apparatus particularly designed to employ atmos- 'pherlc air or other gaseous fluid to eff-ectllota- Y on said line; showing the oscillatory impeller operatively connected with a rheostat for controldischarged into the casing, wherebygravitative separation is effected. An outlet .is provided extending laterally at the lower end of the casing through which the material precipitated in the casing is discharged.

It ishighly important to the emciency of such apparatus to provide means to .variably limit,

predetermine, and control the back pressure of ling the electric motor for driving the fluid pump shown at the right hand side of Fig. I and indicated diagrammatically at the right hand side of Fig. VI. Fig.'VII is a. diagrammatic elevation, partly in section, of a portionof the apparatus at the upper end of Fig.` I, but Ona-larger scale. Fig. VIII is a diagrammatic elevation, partly in section, similar to'Fig. VII but showing apparatus particularly designed to employ atmospheric airor other gaseous lluid vto veff-ect flotation of the solid materials. 2 7

Referring to. Figs..I and II; the masonry base I supports the metallic tower comprising the four vertical I-beam columns 2 connected by horizontal girders 3 capped by the overhanging roof v i As indicated in Fig. I, said pump I6 is actuated by the electric motor I1 and receives the classi# fying iluid through the conduit I8 extending to any suitable source of supply, for instance, a subjacent body of water.

Said separator casings each have an axial inlet conduit for the flotation iluid extending vertically therethrough in coaxial relation therewith and respectively indicated at 6a, 1, etc. Each of said axial conduits is connected with two distinct flotation fluid supply conduits respectively above and below the casing and extending from said supply column conduit I5; the lower conduits being indicated respectively at 5b, 6b, 1b, etc., and the upper supply conduits being indicated respectively at 5c, 6, 1, etc.

4Each of said separator casings has an outlet conduit extending tangentially from the ,upper part thereof and into the next higher casing, and indicated respectively at 5d, 6d, 1, etc. Said conduits 5d, 6d, 1d, etc., conduct the lighter material which is not precipitated in the respective casings 5, 6, 1, tc. Each of said casings has an outlet conduit extending laterally at the lower end thereof through which the material precipitated in the casing is discharged; such conduits being indicated at 5, 6, 1, etc.

The material to be treated, for instance sand, is conveniently dredged from its natural bed and delivered mixed with water into the tank 20, indicated in Fig. I, through a rotary screen which eliminates particles larger than it is desired to treat. Said material to be treated is raised, mixed with water, through the conduit 2| by the centriIugal pump 22 from which it is discharged through the conduit 23 tangentially into the conical side of the lowermost separator 6, as indicated in Fig. I. Said pump 22 is conveniently actuated by the electric motor 25.

As shown in Fig. IlI; I nd it convenient to variably predetermine the maximum pressure to which the iluid in the supply column I5 may be subjected, by such means as disclosed in my Pat'ent 2,104,531, to wit, by maintaining the upper end of said conduit normally closed by the valve 21 which may be variably weighted in accordance with the numberI of cast iron pigs 26 placed therein. When that pressure is exceeded, said valve is lifted by the fluid in the column I5 which spills over into the hood I6 and escapes to waste through the conduit 29. However, in accordance with the present invention, that loss is 'G column I6 is initially subjected by the pump 22,

as hereinafter described as connected to conduit I2d -for controlling the pump I6.'

Such control of the initial pressure, and rate of ilow of the stream of flotation fluid carrying the solid material in the several separator casings connected with pump I6, asvabove contemplated, is effected by the means shownin Figs.

II,III, and VI, as follows:

As best shown in Fig. III, the outlet conduit I2d for the uppermost separator casing I2, through which the lightest solid material not precipitated in said separator'is discharged, directs such discharge into the iloat chamber 3| of the control casing 32, through passageways upon opposite sides of said chamber 3| formed by vertical partitions 3I, each of which has several openings 3|'l therethrough leading to said chamber. In order to variably predetermine the rate of discharge of flotation fluid from said iloat chamber and thus predetermine the eiect of that fluid in said chamber upon the float 36; I nd it convenient to provide the bottom of said'chamber 3| with the seat 3|b for the disk 35 having the oriilce 35'. I provide a series of such disks with orices of diilerent sizes which may be selectively utilized to thus determine the quantity of fluid dissipated from said float chamber which passes to waste through the outlet conduit 32' of said control casing 32. y

Said iloate34` is connected by the pivot 36' with the lever 36 which is fulcrumed on the pivot 36' in the bracket 32* fixed on the left hand wall of the valve chamber 32b in said control casing 32. Said lever 36 has rigidly connected therewith two arms 36n and 36 respectively extending upward and downward from said pivot 36' and respectively pivotally connected with valve plunger screws 38 and 39. The cylindrical valve plungers 3|!s and 39l are respectively axially adjustable upon said screws 38 and 39 which carry lock nuts 38h and 39h by which said plungers may be secured in adjusted position.

Said valve plungers 38* and 39* are respectively mounted for axial reciprocation in valve casings 60 and 4| respectively housing ball valves III* and lI. Said ball valves respectively control the openings of the ends of the two uid conduits l2 and I3 leading from the iluid motor casing I5 shown in Figs. II and VI.

As shown in Fig. VTI, the conduit 29 is provided withjcontroltanchanism similar to that shown in'gglg. III as onnected to the outlet conduit I2.,

' I provide a 'series ofxsuch disks with orices of diil'erent sizes which nay be selectively utilized to thus determine the quantity of iluid dissipated from said iloat chamber through the conduit |32' o'f said control casing |32.

Said float |34 is connected by the pivot |34' with the lever |36 which is fulcrumed on the pivot |36' inthe bracket |32* fixed on the lett hand wall of the valve chamber |32h in said control casing' |32. Said lever |36 has rigidly connected therewith two arms I 36'l and 'I 36b respectively extending upwardly and downwardly from said pivot |36' and respectively pivotally connected with valve plunger screws |33 and |39. The cylindrical valve plungers |33- and |33l are respectively axially adjustable upon said screws I38 and |39 which carry lock nuts I38b and |39b by which said plungers may be secured in ad'- justed position.

Said plungers |38a and |39a are respectively mounted for axial reciprocation in valve casings |40 and I4I respectively housing ball valves I4|Iil and I4Ia. Said ball valves respectively control the openings ofthe ends of the two iluid conduits 42 and 43 leading from the fluid motor casing 45.

As shown in Figs. II and VI, said motor casing 45 is a cylinder conveniently supported with its axis in horizontal position by rigid connection with the rectangular rheostat casing 46. .As shown in Fig. II, said motor'casing 45 has rigidly connected therewith the partition 45a, supporting the vertically reeiprocatoryA bearing 45h for the shaft 41 of the oscillatory fluid impeller piston blade 41a. As shown in Figs. l1 and VI, said stationary partition 45a carries three vertically extending springs 45c which continually stress said bearing 45h upwardly to seal its junction with shaft 41. AThe sealing shoe 41b on the outer end of said impeller`41 incloses the at spring 41', which stresses it in contact with the inner cylindrical surface of said motor casing 45. The space in said casing 45 is thus divided into two opposite uid chambers 48 and 49, respectively supplied with uid through the ports 48a and 49a leading from the uid supply conduit 56.

As shown in Fig. II; said conduit 50 is cont-inually supplied with uid under pressure, conveniently clear water, by means of the pump 5| actuated by the electric motor 52 to draw the supply of fluid through the conduit 50 leading to any suitable source of water. ply conduit 5|lleading to the motor casing 45 has the by-pass conduit 50b provided with' the pressure gauge 5U showing the fluid' pressure in said conduit 56. Said by-pass conduit 5|)b opens into the valve casing 5|!d and is normally closed by the ball valve 54 under pressure of the spring 54a, which pressure may be varied by th'e adjusting screw 54b to variably determine the pressure at which the fluid may escape from said conduit 50 back into the conduit 5|)a to the suction side of the pump 5|.

The construction and arrangement above described are such that with the oat 34 supported in the position shown in Fig. III, by` the water in the oat chamber 3|; each of the ball valves 40a and 4Ia is slightly open to the same extent. In that position the Water pressure in the two chambers 48 and 49 of the motor casing 45 is equal and the impeller blade 41a occupies a vertical position betgveen said chambers. However, if said fioat 34 is uplifted from the position shown in Fig. III by accumulation of water in said float chamber 3|, the ball valve 4|l is moved to close the end of said conduit 42 and the ball valve 4| is correspondingly opened to increase the eec- .tive open area of the end of said conduit 43.

Consequently, the impeller. blade which isbalanced in vertical position by equal pressures in the chambers 48 and 49, is displaced counterclockwise, as indicated in Fig. II, by increment of pressure in the chamber 49 and decrement of pressure in chamber 48 with which said conduits `42 and 43 arerespectively connected. On the l contrary, if said oat 34 is lowered by subsidence of water in the float chamber 3| shown in Fig. III; .said impeller 41n is turned clockwise by increment of pressure in the chamber 48 and decrement of pressure in the chamber 49.

Said water sup-A I utilize such voscillatory movement of the impellerelement 4'Ia to control and vary the fluid pressure in the solid material supply conduit 23 and separator, casings 5, 6, 1, etc., by the pump 22, by varying the amount of resistance in, th'e energizing ycircuit of the pump motor 25. Similar oat, valve, and motor control devices are connected with the conduit 29, to control the motor I1 and pump I6.

To thus control the motor circuits and consequent speed of operation of the pumps and consequent pressure, acceleration and deceleration of flow, of 'fluids in the system; I connect the shaft 41 .of the oscillatory impelleri 41a with a rheostat drum` 56 indicated by the dotted circle in Fig. II and shown, principally in elevation, in Fig. VI. As shown in Fig. VI, the drum 56 is arranged to control the motor I1 which, as indicated in Fig. I, is operatively connected with the pump I6 supplying otation fluid to the column conduit I5. Said drum 56 has the arcuate contact plate 56a secured thereon in cooperative relation with the spring switch contact 51, the upper end of which is rigidly connected with the stationary switchbar 46a in said rheostat casing 46 and connected by the electrical conductor I1 with the commutator I1h by the brush I1. The brush I1d is connected with the electrical conductor I1 leading to the resistance grid 58 which has a seriesof branch conductors 59 leading from different portions thereof to respective similar springswitch contacts 60 rigidly connected at their upper ends with said switch bar 46a and overhanging said drum 56, as shown in Figs. II and VI. Said drum 56 has a series of arcuate switch contact plates 56b of different lengths rigidly secured thereon. Said arcuate switch contact plates 56b are all connected in multiple with said contact plate 56B, with the effect that as said rheostat drum 56 is turned in the direction of the arrow marked thereon in Fig. VI by counter-clockwise movementv of the impeller 41B, as shown in Fig. lll; the resistance in the circuit of the motor I1 is increased by inclusion of more of the resistance grid 58 than in the position shown in Fig. VI; with the effect of decreasing the speed of rotation of said motor I1 and consequent decrease\of speed in the rotation of the pump I6 and consequent reduction in the initial pressure of the fluid supplied through the co1- umn I5. On the contrary, when the impeller 41a is turned clockwisein Fig. II, the resistance in the circuit of said motor I1 is decreased by insaid motor I1 and pump I6 and increment in the.

initial pressure of the flotation fluid supplied through said conduit I5 and the series of separator casings 5, 6 ,1, etc. As above indicated, the purpose and eifect of such automatic control of the pressure of the flotation uid in the apparatus described is to compensate for the frequently recurring irregularities in the back pressure of the' uid in said apparatus, however occasioned 'and by accelerating or decelerating the flow of the stream of fluid supplying the material to be separated, or the stream of clear flotation fluid, orboth, independently, simultaneously or at different instants, but with continuing cooperation' in attaining the desired control and regulation of the separting effect desired.

However, in some locations it is more convenient to drive the pumps I6 and 25 by connections with oil 'engines than by connection with 'electric motors. Therefore, as shown in Fig. VI,

I provide the right hand end of said rheostat drum 56 with the axial shaft 41, thus operatively connected with the shaft 41 of said impeller, to drive the gear 41f which may be operatively connected with a valve controlling the operation of such an engine to thus mechanically control such an engine or engines by the operation of a fluid motor such as shown in the motor casing 45, instead of thereby effecting electrical control of an electric motor or motors.'

Although I prefer to use water as the flotation fluid for natural sands, comminuated stone, and coal, as above noted, I may use atmospheric air or other gaseous uids to effect flotation of other solid materials and I have shown in Fig. V apparatus similar to that shown in Fig, III, except that it is adapted for use of such lighter flotation fluids.

In Fig. V, the control casing 62 is similar to the control casing 32 except that it is normally maintained closed to prevent escape of the lighter fluids under'pressure, by means of hinged lids 62a and 62b respectively covering the oat chamber 64 and the valve chamber 65, both of which may be conveniently clamped in air tight relation with the casing 62 by the nut 62 on the bolt 62d. The float 66 is a disk pivoted at 66 on the lever 61 which is like the lever 36 and similarly inder 64' ofthe float chamber 64 by the com-I pressed air or other gaseous fluid in the chamber 68 with which the outlet conduit |2d of the separator I2 is connected as shown'in Fig. V. The bottom of the chamber 68 is provided with any selected one of a series of perforated disks 69, similar to the disk 35 aforesaid, to determine the volume of flotation fluid which is dissipated from said chamber 68 and discharged from the control casing 62 by way of the conduit 10 which may lead to the atmosphere or to a dust collector. As said disks 69 are not accessible from the top of the control casing 62 as are the disks 35- .tion of other solid materials, the conduit 29 is provided with control mechanism similar to that shown in Fig. V as connected to th'e outlet conduit |2d. The discharge from the conduit 29 is directed into the control casing 62, similar to the control casing |32, except that it is normally maintained closed to prevent escape of the lighter fluids under pressure, by means of hinged lids |621i and |62b respectively covering the oat chamber |64 and the valve chamber |65, both of which may be conveniently clamped in airtight relation with the casing |62 by the nut |62c on the bolt |62d. The float |66 is'a disk pivoted at |66' on the' lever |61, which is like the lever |36 and similarly arranged to operate ball valves |40*ab and l|4|a to controlthe outlet for the conduits 42 and 43 as described. Said' float I 66 is normally upheld in the position shown in Fig. VIII in th`e cylinder |64'` of the float chamber |64 bythe compressed air or other gaseous fluid in the chamber |66 with which the outlet conduit 29 of the hood I5' is connected, as shown in Fig. VIII. The bottom of the chamber'l68 is provided with any selected one of a series of perforated disks |69, similar to the disk |35 aforesaid, to determine the volume of fluid which is dissipated from said chamber |66 and discharged from the control casing 62 by way of the conduit |10 which may lead to the atmosphere or to a dust collector. As said disks |69 are .not accessible from the top of the control casing |62, as are the disks 35 used with the control casing 32 in Fig. III, I find it convenient to provide the bottom of the control casing 62 with a removable service door |62e which is normally secured in fluid-tight relation with said casing |62 by nuts |62f.

However, an essential feature of my invention is that tendencies to irregular operation of the apparatus and uctuating back pressure of the fluids therein from instant'to instant are controlled and the operation rendered substantially uniform despite such variations in the nature or rate of supply of the solid material, by controlling means dependent for its operation upon the fluctuating quantity of flotation fluid discharged from the `apparatus whether the apparatus comprises one or more such casings; such control being effected by varying the initial pressure under which flotation fluid is supplied to the apparatus, and thereby accelerating or decelerating the flow thereof in the apparatus, and specifically by controlling the rate of operation of a pump or pumps. An adjunctive feature' is that the fluid discharge outlet, used for such control, is provided with means for rendering its effec- `tive area adjustably variable; the latter means being exemplified by the perforated plates 35 and 69, shown respectively in Figs. III and V.

Therefore, I do not desire to limit myself to the precise details of construction, arrangement, or method of operation herein set forth, as'it is obvious that various modifications maybe made therein without departing from the essential features of my invention as defined in the appended claims.

I claim:

1. In means for separating particles of solid material by flotation, the combination with a series of vertical conical separator casings disposed at different levels, in an ascending series, each having a tangential inlet at the lower portion thereof and a tangential discharge `outlet Yat the upper portion thereof, the discharge outlet of the lowest casing being connected with the inlet\of the next higher casing, and so on in the series; of means" for supplying the material to be' separated, in flotation fluid, to the lowest casing in the series, and thence to the other casings in the series through L'the' respective outlets and inlets thereof, including a first pump; a vertical conduit column, exterior tosaid casings, but having branches respectively extending axially through said casings and connected with said column at both the lower and upper ends of said branches; means for maintaining said column charged with dotation fluid, free from solid material, including a second pump in communica- 'tion, with the lower end of said column; and

means for automatically variably controlling the centrifugal force of the fluid tangentially injected into said casings from said first pump, and the levitating effectof the fluid delivered into said casings from said second pump, by variations in the speed of operation of each 'of said accepta pumps, respectively in accordance with variations in the viscosity of the iluid 'discharged through two variably restricted outlets, respectively from the uppermost casing, and from the top of said column, and thereby increasing the speed of operation of said pumps and consequent kinetic pressure upon said fluid in accordance with increase in viscosity of the fluid, and vice versa, including two pump control casings one in communication with the tangential discharge outlet from the uppermost conical separating casing, arranged to receive fluid from said outlet, and the other in communication with the top of said column, a restricted orifice at the bottom of each of said control casings, respectively determining therat'e of the ow of iluid from said casings, in accordance with the variable viscosity of the uid from the tangential discharge and in accordance with the variable volume of iluid discharged from the top of the column; two elements respectively subjected to the action of the uid in said control casings and movable up and down therein in accordance with the respective temporary level of the uid in said casings; valve means respectively in controlling relation with the speed of operation of said iirst and second' Dumps and respectively operatively connected with said movable elements and arranged to be opened and closed in accordance with the verticallmovements of said elements by the uid ini,

the respective control casings; whereby the rate of operation of each of said pumps is automatically Varied in accordance with the variation in viscosity of the fluid from the tangential discharge and inaccordance with the variable Volume of uid discharged from the top of the column during its operation.

2. In means for separating particles of solid material by flotation, the combination with a series of circular separator casings disposed with their axes vertical, at dierent levels in an ascending series, each having a tangential inletat the lower portion thereof and a tangential discharge outlet at ,the upper portion thereof, the discharge outlet of the lowest casing being connected with the inlet of the next higher casing,

and so on in the series; means for supplying the` material to be separated, in flotation iluid, to the lowest casing in the series, and thence to the other casings in the series through the respective outlets and inlets thereof ,including a first pump; a vertical conduit column, exterior to said casings, but having branches respectively extending A axially through said casings and connected with the column at both the lower and upper ends of said branches; means for maintaining the col- `umn charged with flotation uid, including a second pump; and means for automatically controlling the centrifugal force ofthe fluid tangentially injected into said casings from said rst pump, and the levitating effect of the fluid delivy column, a restricted orifice at the bottom of each of said control casings, respectively determining the rate of the flow of fluid from said casings, in accordance with the variable viscosity of the fluid from the tangential discharge and (in accordance with thevariable volume of fluid discharged from the top of the column; two elements respectively subjected to the action of the fluid in said control casings and movable up and down therein in accordance with the respective temporary level of the fluid in said casings; valve means respectively in controlling relationwith the speed of operation of said first andsecond pumps and respectively operatively connected with said movable elements and arranged to be opened and closed inaccordance with the'avertical movements of said elements by the fluid inl v the respective control casings; whereby the rate of operation of each of said pumps is automatically varied in accordance with the variation in viscosity of the fluid from the tangential discharge and in accordance with the variable vol-4 ume of fluid discharged from the top of the column during its operation.

3. In' means for separating particles of solid material by flotation, the combination .with a i in the series, and thence to the other casings in 1 the series through the respective outlets and inlets thereof; a vertical conduit column, exterior i to said casings, but having branches respectively extending axially through said casings and connected with said column at both the lower and upper ends of said branches; means for maintaining said column charged with otation fluid,

connected with the lower end of said column;

and respective means for automatically varying the centrifugal force of the fluid injected tangentially into said casings, and 'the levitating effect of the iiuid delivered into said casings from said column, respectively in accordance with variations in the viscosity of the uid discharged, including two pump control casings one in communication with the tangential discharge outlet from the uppermost conical separating casing,

` Vthe other in communication withl the top of said ered into said casings from said second pump,

by variations in the speed of operation of each of said pumps, respectively in accordance with down therein in accordance with the respective temporary level of thev fluid in said casings;v

valve means respectively in controlling relation with said means for supplying the materials to, .be separated land said meansefor maintaining 'said column charged with notation fluid and res pectively operatively connected with said movable elements and arranged to be opened and 4closed in accordance with the vertical movements of said elements by the iluid in the respective `control casings; whereby the rate of supply of the material to be separated in said casings and the rate f Charging said column with flotation iiuid is automatically varied in accordance with the variation'in viscosity of the fluidfrom the tangential discharge and in accordance with the variable volume ofiluid discharged from the top o! the column during the supplying and charging operations.

4. In meansfor separating particles of solid material by notation, the combination with a ver-f tical conical separator casing disposed with its apex downward, having a tangential inlet at the lower portion thereof, and a tangential discharge outlet at the upper portion thereof; means for supplying the material to be separated, in notation uid, through the tangential inlet in the casing, including a ilrst pump; a conduit column, exterior tothe casing, but having a branch extending axially through the casing and connectedl with the column at both the lower and upper ends of the branch; means for maintaining the column charged with flotation fluid, free from solid material, including a second pump; and respective means for simultaneously automatically controlling the centrifugal force of the fluid injected into the casing' from the rst pump, and

the levitating effect of the fluid delivered into .iluid from said casings, in accordance with theA variable viscosity of the uid from the tangential discharge and in accordance with thevariable volume of iiuid discharged from the top oi' the column; two elements respectively subjected to the action of the fluid in said control casings and movable up and down therein in accordance with the respective temporary level of the fluid in said casings; valve means respectively in controlling relation with said means for supplying the material to be separated and said means foi maintaining said column charged with flotation iluld and respectively operatively connected with said movable elements and arranged to be opened and closed in accordance with the vertical move# ments of said elements by the uid |in the respective control casings; whereby the rate of supply of the material to be separated in said casings and the rate of charging said column with otation fluid is automatically varied in accordance with the variation in viscosity of the iiuid from the tangential dischargeand in accordance with the variable volume of iiuid discharged from the top of the column during the supplying and charging operations.

5. In means for separatingy particles of solid material by flotation, the combination with a circular separator casing disposed with its axis vertical, having a tangential inlet at the lower portion thereof, and a tangential discharge outlet at the upper portion thereof; a iirst pump means for supplying the material to be separated,

in :dotation iluid, through the tangential inlet in the casing; a vertical conduit column, exterior to the casing, but having a branch extending axially through the casing and connected with the column at both the lower and upper ends of the branch; a second pump means for maintaining the column charged with flotation fluid; and respective means for automatically controlling the centrifugal force of the fluid injected tangentially into the casing, and the levitating effect of the iluid delivered into the casing from the column, by variations in the rate of supply of fluid from each of said pump means, in accordance with variations inthe viscosity of the fluid discharged `from the outlet of the casing, and from the top of the column, and thereby increasing the rate of supply and consequent pressure upon the uidin accordance with increase in viscosity of the uid, and vice versa, includingy two pressure control casings one in communication with said tangential discharge outlet, and the other in communication with the top of said column, a restricted orice at the bottom of each o! said control casings respectively determining the rate of the flow of the fluid from said casings, in accordance with the variable viscosity of the fluid from the tangential discharge and in accordance with the variable volume of fluid discharged from the top of the column; two yieldable elements respectively subjected to the action of the fluid in said control casings and movable up and down therein in accordance with the respective temporary level of the iluid in said casings; valve means respec- A'tively in. controlling relation with each of said pump means and respectively operatively connected with said movable elements and arranged to be opened and closed in accordance with the vertical movements of said elements by the uid in the respective control casings; whereby the rate of operation oi each of said pump means'is automatically varied in accordance with the variation in viscosity of the iluid from the tangential discharge and in accordance with the variable volume of fluid discharged from the top of the column during its operation.

6. A structure as in claim 5; wherein the means for varying the pressure upon the fluid includes a lever supporting the yieldable velement arranged to be levitated by back pressure of the fluid ad- .jacent to the'variable restricted outlet, from the top of the casing, in accordance with variations in the viscosity'of the fluid; said yieldable element being raised as the viscosity increases, and vice versa.

7. A structure as in claim 5; wherein the means for varying the pressureOupon the fluid includes a lever supporting the yieldable element arranged to be levitated by back pressure of the iiuid adjacent to the variable restricted outlet'from the top of the column, in accordance with variations Iin the viscosity of said fluid,.said yieldable element being raised as the viscosity increases, and vice versa.

8. Apparatus as in claim 4; includinga motor casing enclosing two iluid chambers, an oscillaby, said valves control the admission of iiuld to.

said chambers and vary the position of said imf peller in accordance with the variations in vistor casings, each enclosing two fluid chambers and an oscillatory motor impeller continually separating said chambers and subjected to the opposed pressures of iluid in said chambers, and having two fluid conduits leading respectively from said chambers to the two automatically operative valves at one of the two pressure `control casings; whereby, the two yieldable elements in the respective pressure control casings, respectivelyvary the position of the two impell'ers in the respective motor casings, in accordance with the variations in viscosity of the iiuids in the respective pressure control casings.

RUSSELL SCOTT ELLIS. 

